Abstract: A hollow cylindrical-shaped, hat-like sleeve is water-tightly joined with the upper end of the riser section of a manhole structure. The free end of the sleeve is trimmed so that its upper edge fits beneath the shoulder of the frame supporting the manhole cover to prevent subsurface water from entering into the manhole interior through the regions between the manhole cover supporting frame and the top of the riser section, which is usually fitted with adjustment rings to bring the manhole cover frame up to grade. The sleeve is easily cut to any height to accommodate either a greater or lesser number of height adjustment rings. The sleeve flange may be cast into the riser section, or alternatively be placed upon the riser section and water-tightly sealed in place by gaskets. The sleeve flange may be replaced by a gasket-like water stop arranged about the lower end of the sleeve and joined thereto by a suitable waterproof rubber adhesive.